The overall goal of this SBIR Phase II proposal is to develop and validate a fully commercialized instrumented gait analysis system and associated training and reporting tools. Gait dysfunction can dramatically affect a person's ability to perfor activities of daily living, and assessment of gait is a critical component of physical therapy practice. Currently, instrumented gait analysis is inaccessible to the vast majority of physical therapy clinics. Because of this, most clinicians depend on observational gait analysis, which has been shown to have inadequate reliability and validity. Further, two-dimensional gait analysis does not capture many critical three-dimensional (3-D) gait features. Clinical outcomes could be improved if three- dimensional gait deviations could be more objectively quantified in a typical clinic, but current 3-D systems are too space intensive, costly, and technically demanding. The Moir-Phase Tracking (MPT) 3-D motion capture system is a novel single-camera 3-D motion tracking technology that fills the gap between clinical need and currently available 3-D systems. Through innovation in the use of moir patterns generated by a lightweight, multi-layer passive optical target, the MPT technology is able to determine 3-D information with a single camera. The MPT system's single camera operation, automatic tracking of multiple targets and robustness to lighting conditions make it less technically demanding and overcomes the barriers for broad clinical use of instrumented gait analysis. Metria Innovation is developing the MPT-GAIT system for clinical deployment. The aims of this proposal are to 1) adapt a simple and reliable measurement protocol with automated registration assessment, 2) develop a clinically meaningful reporting tool that references against a normative database, 3) engineer robust hardware and software for clinical use that is economical and achieves a high level of ease-of-use, and 4) deploy clinically for system evaluation and refinement. The outcome of this project will be a commercialized instrumented gait analysis system that requires a minimum of dedicated space, is low cost, and has a very high level of ease of use.